This proposal is to request support for a Keystone Symposia meeting entitled "Angiogenesis and Lymphangiogenesis in Cancer", organized by Lee M. Ellis and Luisa Iruela-Arispe, which will be held in Big Sky, Montana from January 6 -11, 2009. A concrete understanding of the mechanisms that regulate tumor angiogenesis has led to advances in the clinic; however multiple challenges remain. First, not all tumors or tumor types respond equally well to anti-VEGF therapy. And for those that do, many, if not all, eventually become refractory to anti-VEGF therapies. It is essential to understand the various factors that lead to the development and function of the neovascular network in tumors in order to improve therapies and identify predictive markers. In addition, understanding basic mechanisms of angiogenesis will lead to insights into other diseases where neovascularization is an important factor in the progression or resolution of the pathology. This symposium will provide a forum to discuss the current status of anti-angiogenic therapy, new insights into the molecular and morphologic abnormalities of the tumor vascular network, methods to investigate mechanisms of angiogenesis, the relationship of the tumor microenvironment to vascular and tumor stem cells, and elucidation of recently discovered mediators of angiogenesis. [unreadable] [unreadable] [unreadable]